How exactly does a nuclear bomb work as well as how does it create radiation and destroy so much with such a little action?
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Atoms are held together with a tremendous amount of energy, and splitting them releases all this energy. A single split atom will not do much by itself the way that a tiny drop of boiling water landing on you will not do much, but if you have a ton of them together and can cause a chain reaction where some of the energy that a split atom releases goes into splitting other atoms, then you have enough energy there to do a lot of damage.
Radioactive materials are unstable which makes it easier to split their atoms, so that’s why they’re picked to split. With most/all other elements, you wouldn’t realistically be able to cause a chain reaction because they’re so stable
It’s not splitting one atom.
When you split one atom, it releases neutrons to split more atoms. Which release even more neutrons, which split even more atoms.
It can become exponential, and energy is released as you split more and more and more atoms, until the bomb breaks apart from the explosion.
Because splitting uranium 235 releases two or three neutrons that then go on to split two or three more uranium atoms. One atom doesn’t have that much energy but the chain reaction means it will go on to split millions of atoms that make it so dangerous.
It doesn’t always have to cause an explosion either. In power generation the goal is to absorb those extra neutrons so each fission of a uranium atom only splits one other uranium atom. That way you can burn it at a constant rate.
As to the why, it comes down to the fact that the things uranium splits into require less energy to bind together than uranium so when it splits there is some extra energy left over that is released as heat/radiation.
To echo other comments: The nucleus of an atom is made up of protons and neutrons, which attract each other with what is often called ‘strong nuclear force.’ This attraction holds so much energy it actually *reduces* (think of it as borrowing) part of the mass of the nucleus to hold itself together (aka ‘mass defect’).
When that nucleus is forced to break up (in nuclear reactions like fission or fusion) then some of that binding force (the mass being borrowed as energy for the strong nuclear attraction) gets converted to pure energy. This conversion, famously depicted as “e = m* c^2” means that part of the mass defect in the nucleus gets multiplied by the speed of light times itself, and the resulting energy is released as photons at the site of the reaction.
In real-world, non-nuclear scale, that means a tiny amount of matter gets converted into an enormous amount of radiation in a matter of milliseconds. Some of that radiation makes it out as radio, infrared (heat waves), light, gamma rays, and everything in between, but a lot of that radiation gets absorbed by the fuel for the reaction, the casing or housing, and the air/water surrounding it. That material can only take so much energy before it turns to gas or plasma and explosively expands in any direction it can. This part happens at the speed of light, and is visible as a flash.
That causes another, thermal chain reaction of gas and plasma hitting matter *slightly* farther away, and causing it to turn into hot gas and plasma as well. The total energy being released is so great that it will keep doing this until it stops agitating matter to higher, luminous states that emit more energy- the limit of matter getting agitated and expelling more heat and light is what is visible as a slowly-growing ‘fireball’. It is the hottest, and ironically *least* destructive part of a nuclear explosion.
The next effect is what happens in terms of matter getting moved around by the blast, essentially at the speed of sound rather than light. All that air getting turned to plasma and hot, luminous gas means it’s expanding and pushing other air out of the way. A LOT of mass of air has to make way for a very small mass of it, which suddenly needs to take up a HUGE volume. This overpressure is what causes the shockwave seen in videos, a massive wind blast at hurricane forces and above, extending for kilometers, much MUCH further than the relatively small fireball. The majority of damage from the two bombs used in war, and the rest of the tests, is from this massive displacement of air or water, caused by the rapid expansion of the small amount of matter in the immediate vicinity of the fireball.
Imagine atoms as coil springs that are tightly compressed with rubber bands wound around them. If the rubber band gets cut, the spring will rapidly release all of the stored energy in it. If it’s just a single spring by itself, not a big deal, but if the spring is in a big pile of springs like it, and when it suddenly decompresses it cuts the rubber bands on a few nearby springs and they do the same to their neighbors, you can imagine the chaos that ensues – a chanin reaction / explosion.
Radioactive elements have atoms like large springs with rubber bands just barely big enough to keep them compressed – it doesn’t take much to set them off. Stable atoms have rubber bands that are quite a bit stronger than the spring itself.
I guess that leads to the next question, how do you split an atom?
It goes very much beyond the scope of ELI5 but the book “The Making of the Atomic Bomb” by Richard Rhodes will give you a very detailed understanding of the “how” it works. The book heavily delves into the “why” it was created in the first place and what was going through everyone’s minds as they did it. The vast majority of the scientists involved knew they were on the brink of an amazing discovery but never imagined a bomb was an actual possibility. By the time that was apparent, most either dived in head first to support the efforts of WWII (Allies & Axis) or did everything they could to stop it.
The strong nuclear force dun it. Atoms are made up of positive protons, negative electrons, and neutral neutrons. The strong nuclear force holds the nucleus (the center) of the atom together which is made of positive protons and neutral neutrons. This force as you might imagine is strong, really strong. All those positive protons so close to each other! its like if you were trying to force to positive ends of a magnet together! But it does! thats how strong it is.
As you might imagine that’s a of energy holding it together. a nuclear reaction is actually harvesting that energy that’s holding atom together. Splitting an atom separates it into multiple smaller ones and releases a bunch of that energy that was holding the larger atom together! Some of the particle that are produced from splitting the atom types of radiation, Alpha, Beta, depending on the size of the particle or Gamma for high energy light wave.
Imagine a stretched rubber band, what happens when you cut the middle? The stress contained within is released. All reactions that release energy do varying amounts of this.
Chemical ones utilize forces between electrons, they are rather weak (compared to nucleus forces).
An atom’s nucleus however has very strong forces holding it together, if you manage to split it, you release all that, causing a much bigger release than would happen with chemical reactions.
In actuality, it is a bit more complicated, heavier atoms, you would use fission to release energy. Lighter atoms you use fusion to gain energy, but this is ELI5 anyway.
Making bonds requires energy, breaking bonds releases energy.
(In fact both processes require an input of energy, but one reaction is endothermic and the other is exothermic)
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